Canonical has switched its cloud software stack to the open-source OpenStack, the company announced Tuesday. The current version of its Ubuntu Server, version 11.04, uses the Eucalyptus platform.

Ubuntu Server 11.10 will include the OpenStack stack as the core of the company's Ubuntu Enterprise Cloud (UEC) package. The server release will also include a set of tools to help users move their cloud deployments from Eucalyptus to OpenStack.

Canonical still plans to support Eucalyptus as a standalone application in future versions of the server software. Users of the Ubuntu 10.04 LTS (Long Term Support) edition will be supported until April 2015. The next LTS release, version 12.04 -- due in April 2012 -- will feature OpenStack.

Canonical did not offer a reason for the switch, which it announced at the Ubuntu Developer Summit, being held this week in Budapest.

The core components of Eucalyptus are open source, though the eponymous company behind the technology retains some advanced features only for commercial releases. Some observers have also expressed worry about Eucalyptus' reliance on the Amazon EC2 (Elastic Compute Cloud) APIs (application programming interfaces), which limits the number of public clouds that could be used to host a cloud instance.

Competitors such as VMware have pointed out that the EC2 API is proprietary, even if Amazon allows its reuse in projects like Eucalyptus. Marten Mickos, CEO of Eucalyptus Systems, however, has argued that the Amazon EC2 API is a de facto standard, one widely used across the industry.

Canonical noted that 53 commercial companies--including Dell, Intel and Cisco--have joined the OpenStack initiative. Eucalyptus recently touted that more than 25,000 clouds have been built with its software.